Method for treating sulphur dioxide gas



Sept. l5, 1931.

B. NORDLANDER METHOD FOR TREATING SULPHUR DIOXIDE GS Filed July l, 1929Inventor Birger VV. ordlahder,

His Attovneg.

Patented Sept. 1,5, 1931 UNITED 1- .ernennen NoRnLANnna, on scnnimoran,NEW Yonx, `Assrelvon TQGENERAL Enne@ Tmc COMPANY., .a conronarron'ornnwYoan i r -nmrrisron roza TREATING sUL1 1rU1`-moxInE GAsf -l i 4Iawnannlmeaany-1,1929: seria-ine( 37753261 This invention.'relates-broadly Y to a new and improved method "and,` apparatus-for;treatingsulphur dioxide gas. More specifi-f" cally it relates toanovelmeans and methodfj 5 of removing practically all of the-:sulphurVtrioxide in sulphur dioxide ,Cefa-sf` When sulphur and oxygen v areburned under Aordinary conditionsv to ,formy sulphur dioxide, sulphurtrioxideis alwaysformed.

About 3% S03 is formed even when sulphuris burned in pure dry oxygen,and consider--` ably more, usually about 12%' SO3 Whenfsul l phur isburned in air, eveninthe mostfeifb Y cient types of burnersnovv used.

15 In many cases substantially pure, dry'sul.- phur dioxide gas isnecessary,and anyapprey ciable amount of sulphur trioxide present-Vtherein is highly objectionable. It isknown, for example,thatsulphurtrioxidevfin the presence of moisture' is4 converted tosulphuric acid which attacks metalsverygreadi-ly; AIIL certainv systemsyot refrigeration .Winch ern-- ploy SO2 as the refrigerant, itisfabsolutelyf necessary` to have sulphur' dioxide` gas which y B5 isdryandsubstantially'free troni-S03. In the 'paper industry, for"example,vvhere sul-4 phur dioxide is generally used"to-form-the` fcalcium bisulfite used in the digesters,'anyl ap'-n preciable amount ofS'Qgin theSOzlgas must be avoided since the S03V -reacts with thecalciumoxide used `to form'y calcium sulfate which is insoluble andzclogs uptheapparatus.`

The S03 in SO2 burnerl gasexists in theA form of a very finemistoffcolloid'al dimens' 375.' sions which is extremely.-diiiicu'ltktoremove by scrubbing with Water or-:even' 'allrali.-1;'The-' mistapparently travels right throughs-'the liquid, and only an insignificantamount *is absorbed. Filtration ofthe SO'2`gas through such Viiltermaterials asy asbestos, fralundurn,

sintered glass,- plaster of Parisfsand', etc.,

is notxentirelyV effective, since th'er-iinestv part I'have foundt'hatifSO'3`l is passed through a layer oiinely divided sulphur, a reducV-tion to SO2 'takes place and this reaction'proceeds to completion atroom temperature. rfhis action depends on. the. formation ofen .50.'unstable intermediate oxide,4 sulphur sesqui- Jdecompo'ses to `form SO2and insolubleamor- V phouslsulphur accordingrto the reactionsq- 1 i..QSOSlQS-esgosg the netresult being. 'n l .v

l i i' yeso.,JfzsasogasstzV i f y. This method furnishes a simple'waylofre.- moving; the S03 *from thejSOz'gas, at the same time converting'itintoY SO2),v thusma'kf ingthe total yieldy 100%( i It has beenv'foundthatafter -a ,c'ertainpe-fv riod ottime the sulphur becomes`poisonedl,=- .Byheating the sulphur-*Which has become' in;

very effectively;V vIthis compound is kept at about g-85",` C., 'itfisaiary more ,effec-` tive in reducingfSOS to SO2 fthangordinary;sulphur. V'This is due to the fact that selenium suliid'e"(SeS2')`asp'repared Aby me according to the' Amethods outlinedfin: myvcopen'ding ap-y plication, Serial No. 350,836, vled zMarchfQS,

present invention, has FtWo extremely', active sulphuratoms 1n themolecule.` Y Y y In the accompanying drawings forming `part of thisapplication, Fig-,1 isa view,

brokenk away,` partly' insection .a and partly inyelevation, ofanapparatus Wherebyvmy' invention may Ibe' carried intoedectgand 1928,:assigned to the same.assig'iiee asthe culated therethrough. Thecylinder 1 is provided With a base plate'3, which is preferas bywelding, near its outer circumference the adjacent end of thecylinder 1. Within and coaxial with the cylinder 1 is another cylinder 4of smaller vdiameter which is also suitably fixed, as Vby Welding, tothe base plate 3. The welded end portion of the inner cylinder 4fits'within the. center opening of the base plateV 3. Removably fixed`to the as ff l fying base-plate 3 is another ring member 5 and betweenthe members 3 and 5 a suitable packing 6 is interposed. Suitablyjoinedto the ring member 5 at its central vportion is one end of an elbowff?,the other end ofthe elbowf' being formed ywith a flange 8S Flange 8g isremovably connected to fiange 9 vWhich-is xed'to inlet pipe 1( which in'turn connects `with main pipe-11 through which the SO2 gas to bepurified travels.

ring 5 and serves as a support for the perforated plate 13, which may bemade of any suitable material. 4Vlithin the cylinder or tube 4 is stillanother cylindrical member y14 which has its ends closed as by plates 15and 1 16, and which is rigidly fixed to the inside of the cylinder 4 asbyV membersl 17 suitably. spaced around its surface. Resting on the topend'of the cylinder 1 and "having a grooved ring portion 18 to'receivetheupper end of cylinder 4is the ring member 19. On-

top of this member19 is an annular member 20, similar to the member 5,and fixed thereto .is-one end ofthe elbow 21. To the 'other end of theelbow 21 islfiXed a flangeportion 22 cooperating with and removablyfixed tovange member 23'which is in; turn connected-with pipe24thelatter leading to the outlet pipe 25 for the purified SO2".y

main gas. :Interposed `betweenfmembersl) and 20 .isasuitable lpackingring-26. The members19fand 20 4and packing rings 26 and 27 are clampedtogetherin'conjunction with a Vring;28 whichiisiplaced under thesemembers and surroundsthe outer surfaceof the cylinder 1'. Thespacebetween the Vinner surface of the cylinder 4andw the outer surface ofthe cylinder 14 is practically filled with thepurimedium29, which ispreferably seleniumsulfide. Y f

In Fig. 2 I. 'have' shown an arrangement whereby a lbattery of puriersmaybe 4set upand Aoperated inV accordance with my in-; vention.Ihaveshown forpurposesof illustration'only three of these .unitsconnected to' the main inlet and outlet pipes v11 and V25,'`respectively, for-'the SO2` gas, although it'yv'viillj be apparent thatany number'might beyused. The arrangement is particularly ruseful'rinquantity production when SO2 gas is purified on a large scale'. As willVbe noted, valves 30 control the outlet pipes 24;,of each of the umts,while valves 31 controlthe inlet. pipes 10 of the units. Thisarrangement makes it Y possible to keep any or all of the unit-s goingably in the formof a ring to'which is fixed,

removing bolts 32 holding these members 'together.' Bolts 33 are thenremoved and the member 2Q may be easily removed by sliding the ange 22on the adjacent face of the fiange 23 until clear thereof. The materialmay then be introduced into- .the space be- 13acts as'asupport "for thematerial, and allowsfV the -SO2 gas to ,travel upwardlyA therethrough'.In order"to' remove the'purifying material 29 'from the unit, it ismerely necessary to remove bolts 34and 35 and slide the A r1ng member 12is suitably fixedtotheV tween members 4 and 14. Perforated plate fmember and the parts fixed thereto. downwardly. The material-maybecaught in a suitable containerfpl'aced beneath the unit operated on.VItis, of couse, obvious that the valves 30 and 31 in conjunction withthe unitv being filled or"emptied,"willfbe turned off While theseoperations are carried on. These valves are'fplaced beyond the flangemembers 8, 9r and 22, 23a-nd close to the main inlet andjoutlet pipes,so that no SO2 can` escape into the atmosphere when they are Aturnedoff.

In operation, assuming that the units have and the gas, by the-time itreachesthe entrance to elbow21, is practicallypure SO2 gas". ',ThegpureVgas leaves by outletsy 24, 25 fori use where necessary. Q g

By arranging the purifiedmaterial within tube or ,cylinder 4, and aroundthe hollow vcylinder 14,as shown. a'relatively large sur- 'icsfacewispresented to the SO2 gas and at'the same vtime the purifiedlmaterial is,l more easilv'kept at a uniform temperature.' yVVhile-Ihaveindicatedthe use of the purifying material at' a temperature of 80K-85Ci',"it vis to be understod that the material may beused at roomtemperature as effectively toV remove -SOQ from SO2 gas. When kept `atthe above temperature range seleni- 11m-sulfide is capable Iof beingused longer before it becomesfinactive. s Y

*IfV selenium sulfide is used as the purifying 'material and it becomesinactive its activity may be restored by regrinding the material. Thedecrease in activityis probably. due to the removal of all the activesulphur at the surface, which when inactive always appears black,probably due to the presence of selenthis S03 effectively removedtherefrom. InV

my copending application, Serial No. 372,868, filed June 22, 1929assigned to the same as.- signee as the present invention, I haveprovided means and method for making SO2 gas substantially free fromSOS. Such gas may be further purifiedby means of my pres,- entinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates,"is: l

1. The method of removing substantially all but a trace of sulphurtrio-xide from sul-` phur dioxide gas, which consists in passing suchgas through a body containing active sulphur.

2. The method of removing substantially all but a trace ofsulphurtrioxide from sulphur dioxide gas, whichconsists in passing suchgas through a compound of selenium containing active sulphur therein.

3. The method of treating a gas which consists mainly of sulphur dioxidebut contains an appreciable amount, of sulphur trioxide, whichlcomprises passing such gas through a substancecontaining sulphur inchemically active form as the purifying medium. 4 l

4. The method of removing substantially all but a trace of sulphurtrioxide from sul?.`

phur dioxide gas, which consists in passing such gas through seleniumsulfide.

5. VThe method of removing substantially Y all but a trace of sulphurtrioxide from sulphur dioxide gas, which consists in passing such gasthrough selenium suliide at a temperature of about -85.JV C.V

In witness whereof, I have hereto set my hand this 29thday of June,1929.

BIRGER w. NORDLANDER..

